A Cross-Calibration Study of GE Lunar iDXA and GE Lunar DPX Pro for Body Composition Measurements in Children and Adults

Subcutaneous and Visceral Fat: Relation with Brown Adipose Tissue Activation in Women

Brown adipose tissue (BAT) helps control body weight and is inversely correlated with body fat, but it is unclear whether it is subcutaneous adipose tissue (SAT) or visceral adipose tissue (VAT) that is related to BAT activation. The presented study aimed to verify the relation of SAT and VAT on BAT activation through infrared thermography (IRT) and cold stimulation in adult women. Forty women were evaluated in body composition and skin temperature (Tskin) acquisition by IRT. Student's independent t-test, Pearson's correlation, and two-way repeated measures ANOVA with Tukey post-hoc were applied. Women with low amounts of SAT and VAT had a significant increase in supraclavicular Tskin (SCVT). Medium negative degrees of linear variation were found before and after cold stimulation between SCVT, SAT and VAT. A significant effect of the moment factor and the group factor on the SCVT between subjects divided into the groups were pointed out. No difference was found in the relation between SAT, VAT, and BAT in adult women, pointing out that both types of fat are equally related. These results can help clinical practice understand clearly, through IRT, that the high accumulation of SAT and VAT can impair the activation of BAT and hinder the loss of weight in women.

Are there differences in anaerobic relative muscle power between upper and lower limbs in adolescent swimmers: A blinded study

Success in speed swimming depends on the efficiency of the anaerobic system for the production of cellular energy, especially during muscle power production. In the adolescent athletes much is unknown with regards to the relationships between relative power of upper and lower limbs with speed swimming performance. The aim the present study was to identify differences in relative muscle power of upper and lower limbs in adolescent swimmers and relate these to speed swimming performances. Sixty adolescents, of both sexes (50% female, 50% male, 30 swimmers and 30 controls), were recruited. The relative upper limb power (ULP[W/kg]) was assessed by a medicine ball test and the relative lower limbs power (LLP[W/kg]) by a jump test on a jumping platform. Lean mass of the upper and lower limbs was assessed by dual-energy X-ray absorptiometry (DXA) (g). Sport performance was assessed during national level competition (50-m swimming time [in seconds]). Biological maturation (BM) was indexed by years from attainment of peak height velocity. ULP(W/kg) was higher than LLP(W/kg) in both groups (p ​< ​0.05). Upper and lower limb lean mass (g) correlated significantly with ULP(W/kg) and LLP(W/kg) in both groups (p ​< ​0.05). ULP(W/kg) and LLP(W/kg) correlated with 50-m swimming performance (s), in both sexes (p ​< ​0.05). Advanced BM was associated with ULP(W/kg) and LLP(W/kg) in both groups (p ​< ​0.05), and with 50-m swimming performance (s) in both sexes (p ​< ​0.05). We concluded that ULP(W/kg) is higher than LLP (W/kg) in adolescent swimmers. Upper and lower limb lean mass and BM were both positively associated with increased ULP (W/kg) and LLP (W/kg).

Validity of the relative fat mass pediatric index (RFMp) for the analysis of body composition in physically active youths at different stages of biological maturation

BACKGROUND

The paediatric relative fat mass (RFMp) index was valid for analysis of percent body fat (BF%). However, the validation did not consider biological maturation (BM) stages. The present study aimed to verify the validity of the RFMp index in the estimation of BF% in children and adolescents of both sexes at different stages of BM.

METHODS

A cross-sectional study was conducted with a sample of 146 young (males: 64.5%. females: 35.5%. age: 13.0 ± 2.2 years) practising sports modalities. We tested the validity of four RFMp equations (1: for boys aged 8-14 years; 2: for girls aged 8-14 years; 3: for both sexes aged 8-14 years; and 4: for both sexes aged 15-19 years) to analyse BF% using dual-energy X-ray absorptiometry as a reference method. BM was analysed by peak height velocity (PHV). Thus, we created subgroups by BM stage (pre-PHV, circum-PHV and post-PHV).

RESULTS

Analyses of agreement between methods showed that only the RFMp-3 equation was reliable to analyse BF% in subjects of both sexes aged 8-14 years at the circum-PHV BM stage (proportion bias 95% confidence interval = -0.3 to 0.5, p = 0.7. concordance correlation coefficient = 0.3; validity = 0.9).

CONCLUSIONS

The RFMp equation developed for the paediatric population of both sexes aged 8-14 years was valid for predicting BF% in children and adolescents of both sexes at the Circum-PHV stage of the BM.

Comparison of brown adipose tissue activation detected by infrared thermography in men with vs without metabolic syndrome

BACKGROUND

Brown adipose tissue (BAT) high density of mitochondria and its thermogenic characteristics promote the dissipation of chemical energy in the form of heat, increasing body caloric expenditure, decreasing plasma levels of lipids and glucose (GL). This makes BAT a potential therapeutic target of Metabolic Syndrome (MetS). Position Emission Tomography Scanning (PET-CT) is the gold standard for estimating BAT, but it has several limitations, including high cost and high emission of radiation. On the other hand, Infrared Thermography (IRT) is considered a simpler, cheaper and non-invasive method to detect BAT.

OBJECTIVE

The aim of this study was to compare BAT activation through IRT and cold stimulation in men diagnosed without and with MetS.

METHODS

Sample of 124 (35.3 ± 9.4 years old) men was evaluated of body composition, anthropometric measurements and dual X-ray absorptiometry (DXA) hemodynamics, biochemical tests and body skin temperature acquisition. The Student t-test with subsequent effect size by (d) Cohen and two-way repeated measures ANOVA with Tukey post-hoc comparisons were conducted. Level of significance was p < 0.05.

RESULTS

There was significant interaction between group factor (MetS) vs group moment (BAT activation) in supraclavicular skin temperatures right side (maximum (F_(1,122) = 10.4, p < 0.002, η² = 0.062), mean (F_(1.122) = 13.0, p < 0.001, η² = 0.081) and minimal (F_(1,122) = 7.9, p < 0.006, η² = 0.052)) and left side maximum (F_(1,122) = 7.7, p < 0.006, η² = 0.048), mean (F_(1.122) = 13.0, p < 0.037, η² = 0.007) and minimal (F_(1,122) = 9.8, p < 0.002, η² = 0.012)). The MetS risk factor group didn't present significant increase of SCV temperature BAT after cold stimulation.

CONCLUSION

Men diagnosed with MetS risk factors seem to activate less BAT, when exposed to cold stimulation, compared to group without MetS risk factor.

Cross-calibration of two dual-energy X-ray absorptiometry devices for the measurement of body composition in young children

This study aimed to cross-calibrate body composition measures from the GE Lunar Prodigy and GE Lunar iDXA in a cohort of young children. 28 children (mean age 3.4 years) were measured on the iDXA followed by the Prodigy. Prodigy scans were subsequently reanalysed using enCORE v17 enhanced analysis ("Prodigy enhanced"). Body composition parameters were compared across three evaluation methods (Prodigy, Prodigy enhanced, iDXA), and adjustment equations were developed. There were differences in the three evaluation methods for all body composition parameters. Body fat percentage (%BF) from the iDXA was approximately 1.5-fold greater than the Prodigy, whereas bone mineral density (BMD) was approximately 20% lower. Reanalysis of Prodigy scans with enhanced software attenuated these differences (%BF: - 5.2% [95% CI - 3.5, - 6.8]; and BMD: 1.0% [95% CI 0.0, 1.9]), although significant differences remained for all parameters except total body less head (TBLH) total mass and TBLH BMD, and some regional estimates. There were large differences between the Prodigy and iDXA, with these differences related both to scan resolution and software. Reanalysis of Prodigy scans with enhanced analysis resulted in body composition values much closer to those obtained on the iDXA, although differences remained. As manufacturers update models and software, researchers and clinicians need to be aware of the impact this may have on the longitudinal assessment of body composition, as results may not be comparable across devices and software versions.

Deep learning approach for automatic segmentation of ulna and radius in dual-energy X-ray imaging

BACKGROUND

Segmentation of the ulna and radius is a crucial step for the measurement of bone mineral density (BMD) in dual-energy X-ray imaging in patients suspected of having osteoporosis.

PURPOSE

This work aimed to propose a deep learning approach for the accurate automatic segmentation of the ulna and radius in dual-energy X-ray imaging.

METHODS AND MATERIALS

We developed a deep learning model with residual block (Resblock) for the segmentation of the ulna and radius. Three hundred and sixty subjects were included in the study, and five-fold cross-validation was used to evaluate the performance of the proposed network. The Dice coefficient and Jaccard index were calculated to evaluate the results of segmentation in this study.

RESULTS

The proposed network model had a better segmentation performance than the previous deep learning-based methods with respect to the automatic segmentation of the ulna and radius. The evaluation results suggested that the average Dice coefficients of the ulna and radius were 0.9835 and 0.9874, with average Jaccard indexes of 0.9680 and 0.9751, respectively.

CONCLUSION

The deep learning-based method developed in this study improved the segmentation performance of the ulna and radius in dual-energy X-ray imaging.

The Effectiveness of Biological Maturation and Lean Mass in Relation to Muscle Strength Performance in Elite Young Athletes

This study aimed to identify the interactional relationships between maturation (biological age (BA)) and lean mass on strength development in young athletes from different sports. Using a cross-sectional study design, a sample of 64 young athletes (rowers, swimmers, jiu-jitsu, volleyball, soccer and tennis players) of both sexes (13.6 ± 1.17 years) were recruited. Body composition was assessed using dual energy bone densitometry with X-ray source (DEXA). Strength of upper limbs (ULS), force hand grip (HG), vertical jump (VJ) and jump against movement (CMJ) were recorded. BA was estimated from anthropometrics. BA relationships were identified with upper limb strength in all athletes, and with the lower limb strength of tennis players, only (p < 0.05). An interaction effect between lean mass and BA was found (η2p = 0.753), as was a local effect within the regression models (ƒ2 ≥ 0.33). Athletes with a higher concentration of lean mass had superior upper and lower limb strength (p < 0.05). Lean mass showed a local effect (ƒ2) greater than that associated with BA. Although maturation is related to strength development, the strength of the relationship is mitigated by the accrual of lean mass. Specifically, the local effect of lean mass on muscle strength is broader than that of maturation, especially for lower limb strength.